Satellites use attitude actuators to orient themselves while in orbit. An example of an attitude actuator is a reaction wheel and a momentum wheel. Another example of an attitude actuator is a Control Moment Gyroscope (CMG). It has been well documented that CMGs are superior to reaction wheels in that they require less maneuver time, provide higher torque and consume less power. Furthermore, as CMGs operate on the principle of using the gimbal to incite torque on the satellite, the spinning wheel can be maintained at higher speeds, as compared to reaction wheels, which require a change in the speed of the wheel to incite torque on the satellite.
FIG. 1 shows a CMG. The CMG includes flywheel 1 mounted on gimbal 2. Flywheel 1 rotates about first axis A1 by spin motor 3 and gimbal 2 rotates about second axis A2 by torque motor 4. As flywheel 1 spins, the rotation of gimbal 2 tilts the angular momentum of flywheel 1. As gimbal 2 tilts, the changing angular momentum causes a gyroscopic torque that rotates the satellite.
However due to their design, CMGs are usually heavier and larger than reaction wheels, and are therefore are only suitable for large satellites, and not small satellites. Small satellites usually use reaction wheels and therefore do not reap the advantages conferred by CMGs. Therefore, there exists a need to adapt CMGs for use with small satellites by reducing the mass and volume of CMGs.
There also exists a need to design a housing for the CMG. The objective of the housing is not only to provide additional protection for the CMG, but also to maintain a vacuum-less environment for the CMG to operate in.